1. Field of the Invention
This invention relates to the field of wellbore fluids and more specifically to the field of using wellbore fluids comprising perlite to service a wellbore.
2. Background of the Invention
Natural resources such as gas, oil, and water residing in a subterranean formation or zone are usually recovered by drilling a wellbore down to the subterranean formation while circulating a drilling fluid in the wellbore. After terminating the circulation of the drilling fluid, a string of pipe, e.g., casing, is run in the wellbore. The drilling fluid is then usually circulated downward through the interior of the pipe and upward through the annulus, which is located between the exterior of the pipe and the walls of the wellbore. Next, primary cementing is typically performed whereby a cement slurry is placed in the annulus and permitted to set into a hard mass (i.e., sheath) to thereby attach the string of pipe to the walls of the wellbore and seal the annulus. Subsequent secondary cementing operations may also be performed. One example of a secondary cementing operation is squeeze cementing whereby a cement slurry is employed to plug and seal off undesirable flow passages in the cement sheath and/or the casing.
Cement extender admixtures are typically mixed with the cement to improve the physical properties of the cement. Conventional cement extender admixtures include fumed silica, colloidal silica, flyash, slag, and zeolites. Drawbacks to the conventional cement extender admixtures include a slow rate of ultimate strength development and low tensile and compressive strengths of the resulting cement compositions. Further drawbacks include premature gelation of the cement composition and difficulties with set retardation. Additives such as fibers, elastomers, and latex emulsions have also been developed to improve the physical properties of the cement. Drawbacks to such additives include monetary costs of the additives and a lack of sufficient strength in the resulting composition.
Consequently, there is a need for improved methods of cementing with cement having improved physical properties. Further needs include cement compositions having improved physical properties. Additional needs include improved methods for servicing a wellbore.